AFTER lagging behind rivals Tesco and Asda in the online grocery war, ­Sainsbury’s is ready to win the “appy shopper” battle with ambitious plans to personalise shopping on the go.

It has played catch-up with Tesco with the launch of Sainsbury’s and Nectar smartphone apps which update deals and loyalty card points.

But the chain wants to give mobile phone shoppers an even more personal touch using ­software which will alert users to complimentary deals and products they may have left off their shopping lists.

Group development director Darren Shapland said: “We want to use the digital age to make shopping a better experience.

“For example, if someone has been buying a certain product like Brie ­consistently, we would like to create an app or alert that tells them that there’s a complimentary product on offer, such as grapes or wine, that would go well with it as they shop.

“We don’t want to bombard them with information, just make them aware that they can add a twist to what they are buying.”

I’m with Darren and six other members of the operating board for a tour of the chain’s revamped flagship store in Crayford, Kent.

The 100,000 sq ft food, clothing and homeware empire – the size of three Wembleys – is so vast that shoppers complain about needing spaces to sit down for a breather between ­departments. As I chat with property director Neil Sachdev, one miffed shopper – mistaking him for a floor manager – interrupts to complain.

“There’s not enough seats to have a rest,” she tells him without realising he is the man who oversaw the ­Crayford rebuild.

Neil takes note. “It’s ­important we understand this is a big store and we need to meet their needs,” he says.

Crayford is split over two levels with moving walkways to get to clothing on the next tier.

It’s here that I meet Luke Jensen, managing director ­non-food, who reveals his new signing, fashion guru Gok Wan, will be creating a capsule wardrobe at bargain prices when the range is launched in autumn.

But Luke has already drawn up a summer fashion battle plan to take on John Lewis, M&S and fashion chain Next.

“We benchmark quality against M&S, John Lewis and Next – but our prices are much better,” he says.

And to prove it he shows me a range of summer must-haves – linen trousers adored by celebrities including Cheryl Cole and Katie Holmes for £14. “They’re £22 at M&S,” he tells me.

Luke is also behind their cheeky royal wedding T-shirts – one of which reads: “It could have been me.”

He adds: “The original was ‘should’ but we felt that ‘could’ was less ­aggressive and a tribute to the fact that an ordinary girl has won the heart of a prince.